In order to fabricate lower thermal expansion aluminium alloys, the effects of microstructural parameters such as the volume fraction of SiC_p and the shape and size of Si phase on the coefficient of thermal expansion(CTE) of the spray-cast and hot-extruded hypereutectic Al-Si(A390) alloy composites were investigated experimentally. The CTEs of hypereutectic Al-Si (A390) alloy were changed proportionally with the size of Si phase. Ultimate tensile strength, elongation and Young`s modulus of the spray-cast and hot-extruded specimen were improved dramatically compared to those of the permanent mold-cast specimen. Although Young s modulus of the spray-cast and hot-extruded specimen was improved highly effectively by addition of SiC_p, no improvement was observed for the UTS and elongation. Spray-cast and hot-extruded hypereutectic Al-Si (A390) alloy reinforced with 20vol.%SiC_p exhibits a CTE equivalent to stainless steel.